1. Field of the Invention
The present invention relates to a portable information processing apparatus such as a notebook PC, a cabinet of which is made of lightweight material superior in heat conductivity, typified by magnesium alloy, for example.
2. Description of the Background Art
For a portable information processing apparatus typified by a notebook PC, goals of higher-performance, lower-profile, and lighter-weight have been diligently pursued. The key to higher-performance is a CPU (Central Processing Unit) capable of higher-speed processing and a more highly-integrated circuit. And the key to lower-profile and lighter-weight is a lightweight metal such as magnesium alloy, which does not impair the cabinet strength.
Since such a highly-capable CPU and a highly-integrated circuit generate much heat to raise their own temperature and surroundings"" to a higher degree, an issue here is how effectively the heat is dissipated into the air through the cabinet made of the lightweight material such as magnesium alloy.
With reference to FIGS. 9 and 10, described below is the structure of a conventional portable information processing apparatus, and a heat dissipation method. A portable information processing apparatus PIc1 mainly includes a cabinet 20, a palm rest 21, a display 22, a keyboard 23, a CPU 25, a cooling fan 27, and flat pad 29.
The cabinet 20 is made of metal. The lower-front thereof is the palm rest 21, where a user puts his/her hands to tap keyboard. Found approximately in the center of the palm rest 21 is the flat pad 29, which is a pointing device. The keyboard 23 is placed on the upper part of the cabinet 20, and the display 22 is hinged to the cabinet 20 in a swivel manner.
In the cabinet 20, placed beneath the keyboard 23 is a circuit board 24 having the CPU 25 mounted thereon. Since the CPU 25 itself heats up, a dissipator 28 is placed thereover so as not to abut the cabinet 20. The dissipator 28 is partially in contact with the cooling fan 27. With such configuration, even if the dissipator 28 is heated due to the CPU 25, the heat is dissipated by the cooling fan 27 so that the temperature in the cabinet is kept constant.
In order to adequately cool the heat source, i.e., CPU 25, in the portable information processing apparatus Plc1, the dissipator 28 has to be increased in area and volume for effective heat absorption. Moreover, the cooling fan 27 has to be increased in power for swift heat dissipation so as to improve absorption efficiency of the dissipator 28. The problem here is, if a motor of the cooling fan 27 is increased in speed, noise level and power consumption are both increased.
To get around such problem resulting from the cooling fan 27, the structure of a portable information processing apparatus PIc2 and heat dissipation method are briefly described by referring to FIGS. 11 and 12. Herein, heat generated in the cabinet 20 is intended to go through the cabinet 20 before being dissipated. Specifically, the cabinet 20 is a functional substitute for the dissipator 28, and absorbs the heat of the CPU 25 from the inner surface thereof and then dissipates the heat from the outer surface thereof to internally cool off.
However, the heat absorbed from the inner surface of the cabinet 20 is conducted and resultantly heats the entire cabinet 20 to such degree that the user feels uncomfortable. At such degree, if the user puts his/her hands on the palm rest 21 for a long time, he/she may suffer low-temperature burns. In the above, the cabinet 20 is assumed to functionally substitute for the dissipator 28. However, even if the cabinet 20 and the dissipator 28 are separately provided as in the portable information processing apparatus PIcl, the heat of the CPU 25 is conducted to the cabinet 20 through the dissipator 28, and thus the cabinet 20 is heated beyond the allowable temperature.
The present invention has the following features to attain the objects above.
A first aspect of the present invention is directed to a portable information processing apparatus in which heat conduction from a high-temperature heat-generating component in a cabinet to a palm rest, which is a surface of the cabinet, is restricted, and the temperature of the palm rest is controlled to be no higher than a predetermined temperature, the device comprising:
a heat conducting spacer provided over the heat-generating component to conduct heat thereof;
a heat absorption area being a part of the cabinet absorbs the heat of the heat-generating component through the heat conducting spacer; and
a heat conduction obstructing area provided on a heat conduction path between the heat absorption area and the palm rest to reduce a cross-sectional area of the heat conduction path.
As described above, in the first aspect, the temperature of the palm rest can be controlled to be no higher than a predetermined temperature.
According to a second aspect, in the first aspect, the cabinet is made of lightweight metal superior in heat conductivity and strength.
According to a third aspect, in the first aspect, a cooling fan is provided beneath the heat absorption area in a rather upper position of the cabinet, and dissipates the heat from the heat absorption area to outside of the cabinet.
According to a fourth aspect, in the first aspect, the heat blocked by the heat conduction obstructing area on the way to the palm rest is dissipated from surroundings of the heat conduction obstructing area.
According to a fifth aspect, in the first aspect, an outer surface of the palm rest is subjected to heat insulation.
As described above, in the fifth aspect, the temperature at the palm rest can be suppressed to a greater extent.
According to a sixth aspect, in the fifth aspect, the heat insulation is a thick coating including hollow spheres.
According to a seventh aspect, in the sixth aspect, the heat insulation is a film made of resin.
According to an eighth aspect, in the second aspect, the lightweight metal is selected from a lightweight metal group typically including aluminum and magnesium.
According to a ninth aspect, in the first aspect, the heat conduction obstructing area has one or more through holes formed along the heat conduction path.
As described above, in the ninth aspect, the palm rest can be controlled in temperature without any special device.
According to a tenth aspect, in the first aspect, a cross-sectional area of the heat conduction obstructing area is smaller in size than that of the heat absorption area and the palm rest.
These and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.